JPS6245019A - Formation of thin film fine pattern - Google Patents

Abstract

PURPOSE:To selectively adhere in inorganic insulating film by a method wherein a thin film is selectively grown by utilizing the difference of the surface free energy of the base using a chemical vapor deposition (CVD) method. CONSTITUTION:Perfluoroalkyl acrylate 2 is coated on a semiconductor substrate 1 in the prescribed thickness, and an electron beam 19 is made to irradiate on the prescribed places. The perfluoroalkyl acrylate on which the electron beam is projected is crosslinked, and when flon 113, for example, is used as a developing solution, only the part received no electron beam is selectively fused and removed. Then, when a sample is exposed to the atmosphere of the mixed gas of steam and SiCl4 in a CVD device, the gas molecule is selectively adsorbed and reacted on the part where perfluoroalkyl acrylate pattern 2' is not adhered and high surface free energy is present, and a silicon oxide film 3 of the same thickness as the film 2' can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for forming fine patterns on thin films in the manufacturing process of semiconductor devices.

[Conventional technology]

With the increasing density of integrated circuits, ultra-fine processing with a pattern width of several thousand is becoming necessary.

Such ultrafine processing requires exposure using electron beams, X-rays, or ion beams.

Polymethyl methacrylate (PMMA) used for electron beam exposure has the disadvantage of low sensitivity, requires long exposure times, and has a high enough film thickness to provide etching resistance when processing the base film. There were problems such as unavoidable resolution degradation due to forward scattering and secondary electron scattering.

In an attempt to increase sensitivity, methacrylates with fluoroalkyl in the side chain (Journal of Electrochemical Society (J.

Electrohem, Soc,) Volume 124, 164
8 (1977)) as a resist material, or Langmuir-Blodgett film as a thin film resist (Thin Solid Films).
Solid Films) Volume 99, pp. 1-329 (198
3)) have been proposed, but all of them have the problem of low dry etching resistance. A three-layer resist consisting of resin, inorganic material, and resin is used to enhance dry etching resistance, but the thickness of the upper resin layer is the thickness that provides etching resistance when processing the lower layer inorganic material. is necessary, but the resolution deteriorates as the thickness increases. The most desirable processing method for forming ultra-fine patterns is to pattern an extremely thin resist using a low-energy electron beam and then etch the underlying thin film, or to select a thin film based on the resist pattern. This is a method of forming As a method for selectively forming a thin film, a technique in which thin films are selectively attached based on differences in surface materials is considered to be extremely effective. Since fluororesins have extremely low surface free energy, several attempts have been made to utilize fluororesins for selective attachment of substances. For example, a non-horizontal plate printing method that takes advantage of the ink-repelling properties of water- and oil-repellent fluorine-based photosensitive resins (Japanese Patent Publication No. 51-58105 of Daikin et al., Japanese Patent Publication No. 55-2 of 3M)
7336), and a planarization wiring method in which metal is embedded by selective vapor deposition using a fluororesin film patterned with a photoresist film (Toshiba's Special Publication No. 53-42396).

[Problem that the invention seeks to solve]

However, the lithographic printing method is a liquid phase deposition method, and it is difficult to apply it to fields such as semiconductor manufacturing processes, which require strict requirements for fine dimensions and uniformity of film thickness.

On the other hand, in the planarization wiring method using selective vapor deposition, the fluororesin is heated to around 200'C for planarization and is deposited, so photosensitive fluororesin cannot be used. Furthermore, photoresist must be applied and patterned, and since the vapor deposition of metal atoms is a physical deposition phenomenon and does not involve a chemical reaction, there is little difference in the energy required to form a thin film depending on the surface material. It is difficult to take advantage of the difference in surface material between the film and the underlying film on which the metal is deposited.

Selective deposition is only possible for special metals such as gold, and it is difficult to selectively deposit inorganic insulating films such as metal compounds, making it impossible to use it for microfabrication.

[Means for solving problems]

FIG. 1 is a schematic process sectional view for explaining the present invention in detail. That is, in the present invention, first, a first thin film 2 having extremely low surface free energy is patterned on a substrate 1. Next, perform the CVD (chemical vapor deposition) method,
By utilizing the difference in adsorption energy of reactive molecules with respect to the difference in surface free energy between the first thin film 2 and the portion 27 to which the first thin film 2 is not attached, the portion 27 to which the first thin film 2 is not attached is It is characterized in that the second thin film 3 is selectively grown.

[Effect]

A feature of the present invention is that a thin film is selectively grown using the CVD method depending on the difference in surface free energy of the underlying material. Therefore, the surface free energy of the first thin film patterned on the substrate is:

It is necessary that the surface free energy is sufficiently lower than the surface free energy of the base to which the first thin film is not attached.

In order to explain this surface free energy, the critical surface tension corresponding to the surface free energy is shown for two representative substances. Perfluoroalkyl acrylate (PPFAA), which is a fluororesin that is an example of a thin film with low surface free energy in the present invention, CF, (CF, ), CH,
-The critical surface tension of A is 10.4 dyn/cm, L
Hydrocarbon, which is a typical organic substance used in SI manufacturing, has a rate of 31 dyn/cm, and chlorocarbon has a rate of 40 dyn/cm.On the other hand, Si, a typical inorganic substance used in LSI manufacturing, , etc. are
It has a high surface free energy, 1oodyn/am
That's all. There is generally a difference of this magnitude, that is, a difference in surface free energy level, and the present invention utilizes this difference. This difference in surface free energy affects the magnitude of activation energy when depositing a thin film on one surface when reacting from the gas phase in the CVD method, making it possible to selectively form a film.

FIG. 2 is a diagram showing an example of a CVD apparatus used for selective growth. 28 is the reaction chamber, 29 is the sample, 30.31°32
5iCQ4 and water vapor (H20) are introduced into the reaction chamber 28 using N2 as a carrier gas, and a thin film, in this case silicon oxide (SiO2) Ilg, is selectively grown.

FIG. 3 is a diagram showing the gas flow rate dependence of the thin film deposition rate and the nucleation of the thin film. The horizontal axis indicates the flow rate of the carrier gas N2 for transporting 5iC(1) (the flow rate indicated by the flowmeter 31 in Fig. 2). The flow rate indicated by total 32 is 100 cc/min, and the flow rate of N2 as diluent gas (
The flow rate indicated by the flow meter 30 is.

It is 2.5R/min. The vertical axis on the left is the deposition rate on silicon (person/ffl1n), and the vertical axis on the right is PPF.
In Figure 1, which shows the area occupied by the nucleus of the deposited film on AA/area of PPFAA, 0 corresponds to the vertical axis on the left and indicates the deposition rate on silicon, and ■ and 0 correspond to the vertical axis on the right. , ■
is when 1000 films are deposited on Si, and when the film is deposited on Si,
The figure shows the nuclear occupation area on PPFAA/the area of PPFAA when 2000 films are deposited on top.

As shown in FIG. 3, when the flow rate of the reaction gas of 5iCQ is increased, S iOz nuclei are generated also on PPFAA, which deteriorates the selectivity of film deposition. On the other hand, 5L
When the reaction gas flow rate of C11 is decreased (for example, N
2 flow rate is 0, S i cll, reaction gas pressure only),
It can be seen that while deposition occurs on Si at a rate of about 200 people/sin, conditions are obtained where no deposition occurs on the PPFAA film. This is because when the flow rate of the reactant gas is decreased, the activation energy for film formation increases.
This is because differences in surface materials greatly affect film deposition.

In the selective growth of the present invention, as shown in FIG.
It is not that a thin film such as Si is not deposited on a thin film such as PFAA having low surface free energy, but it is to such an extent that it cannot be recognized as a film.

They attach as atoms and form something like a nucleus on the surface. Such a small amount of adhesion is easily peeled off during the LSI manufacturing process, making it possible to effectively achieve selectivity of 0 or 1.

〔Example〕

Example 1 Fluororesins sensitive to electron beams include, for example, perfluoroalkyl acrylate (CFa(CFz)n(CH)A) or perfluoroalkylmethacrylate (CF, (CF,)nCH2).
-M) (where n>3.A is an acrylate chain, M is a metaliflate chain), and the like.

FIGS. 4(a) to 4(Q) show an example in which a silicon oxide thin film is selectively deposited using perfluoroalkyl acrylate. Perfluoroalkyl acrylate 2 is applied to a predetermined thickness on a semiconductor substrate 1, and predetermined locations are irradiated with an electron beam 19 (FIG. 4(a)). Perfluoroalkyl acrylate that has been irradiated with an electron beam is crosslinked, and when, for example, Freon 113 is used as the phenomenon liquid, only the portion that has not been irradiated is selectively dissolved and removed (see Figure 4).
b)). Next, the sample is placed in a CVD apparatus and exposed to water vapor.

When exposed to a mixed gas atmosphere of 5iC114, the gas molecules selectively adsorb and react with the non-adhered areas of the perfluoroalkyl acrylate pattern 2' with high surface free energy, resulting in a layer with the same thickness as that of the film 2'. A silicon oxide film 3 is formed (FIG. 4(C)). At this time,
The partial pressures of water vapor and 5iC114 are each 10-10
0 T orr was appropriate.

Thereafter, the perfluoroalkyl acrylate film 2' is removed using oxygen plasma or an organic solvent to obtain a desired thin film fine pattern.

Note that if perfluoroalkyl methacrylate is used instead of perfluoroalkyl acrylate, it will be decomposed by electron beam irradiation, so a pattern that is the inverse of the above example will be formed.

In addition, for exposure using ultraviolet light instead of an electron beam, a resist proposed for lithography, such as a copolymer of perfluoroalkyl methacrylate and azide-containing methacrylate (Japan Society of Printing, by Ao Yamaoka et al.,
May 29, 1980 Nα13) etc. may be used.

Furthermore, it is also possible to selectively grow other metal oxides, such as aluminum oxide, molybdenum oxide, etc., and hydrolyzed metal compound gas' (An(CH*)i,
(Aa(i-C,H,), Mo(allyl)4, etc.)
and water vapor.

Example 2 FIGS. 5(a) to 5(d) show an example in which a film with a low surface free energy having a thickness of a molecular layer level was used.

A monomolecular layer of an organic substance 4 having a double or triple bond among chain polymers having a fluoroalkyl group at one end and a parent tree group at the other end is deposited on a substrate 5 by the Langmuir-Blodgett method or adsorption from the gas phase. or deposit a few molecular layers thick (
Figure 5(a)). Examples of this substance include CF s (
CF −)s (CH2)t□CCOOH molecule (IB
There is a U.S. Patent No. 4,169,904 by M. This membrane 4
After irradiating it with an electron beam 20 or ultraviolet rays to crosslink it at predetermined locations (Fig. 5 (b)), a thin film with low surface free energy is patterned when it is exposed to chloroform (Fig. 5 (C)). . Next, the inorganic insulating film 6 is selectively grown using the CVD method as shown in Example 1 (fifth
Figure (d)). Thereafter, the organic film 4' is removed using oxygen plasma or an organic solvent to obtain a desired thin film fine pattern.

Example 3 An example in which the method of Example 1 or 2 is applied to thin film fine pattern formation using dry etching is shown in FIGS. 6(a) to 6(a).
Shown in (e).

A film 8 is deposited on the semiconductor substrate 7, and a resin film 9 is further applied on the film 8 (FIG. 6(a)). Film 8 is M, SL, Si
Any film used in semiconductor devices such as n, etc. may be used. The resin film 9 is preferably an organic film that is selective to the base film 8 to be dry etched, such as various photoresists or polyimides, and the film thickness depends on the thickness of the film 8 to be processed, but it is 5,000 to 1-1. degree is desirable. Next, the film 10 having fluoroalkyl groups used in Example 1 or Example 2 is deposited and patterned in the same manner as in Example 1.2 (FIG. 6(b)). The thickness of this fluoroalkyl group-containing film may be extremely thin, from a monomolecular layer to about 1000 Å or less. First, the inorganic insulating film 11 is coated with the fluoroalkyl group-containing film 10 in the same manner as in Example 1. (Fig. 6 (C)).
)). Next, the resin film 9 is processed using oxygen reactive ion etching using the pattern of the inorganic insulating film 11 as a mask (FIG. 6(d)). At this time, the film 10 is also removed. after that.

Using the resin film 9 as a mask, the film 8 is processed by reactive ion etching using an optimal etching gas (see Fig. 6(e)).
)). At this time, if the film 11 and the film 8 are made of the same material, the film 11 is removed by the etching, but if they are made of different materials, the film 11 is removed before the etching.

Thereafter, the resin film 9 is removed using oxygen plasma or an organic solvent to obtain a desired thin film fine pattern.

Example 4 After forming the pattern 13 of the film having a fluoroalkyl group on the substrate 12 by the method of Example 1 or Example 2 (7th
Figure (a)), organometallic gas e.g. M(CHs)3
By irradiating ultraviolet rays in an atmosphere of about 10 Torr, the film is selectively deposited only on the parts to which the film 13 having fluoroalkyl groups is not attached (FIG. 7(b)), and then, Film 13 is removed to obtain a desired metal film pattern. For example, Cd(CH3)z, Zn(CHl)2, etc. are used as other organometallic gases.
It can be applied to the deposition of other metals such as d, Zn, etc.

Example 5 Using a thin film (for example, a silicon oxide film) 15 selectively formed on a silicon substrate 21 by the method of Example 1 or 2 as a mask, a silicon substrate 21 is coated under normal conditions.
Etching (FIG. 8(a)) and ion implantation (FIG. 8(b)) can be performed.

Example 6 Resin film or carbon film 2 patterned on substrate 23
918(a)), then the surface of the patterned thin film 24 is fluorinated in plasma containing fluorine to form a surface 25 with low surface free energy (FIG. 9(b)).
), Next, in the same manner as in Example 1, a predetermined film 26 is selectively grown on the part where there is no patterned thin film 24 by CVD (FIG. 9(c)). After this, the surface 25 is grown by oxygen plasma.
Then, the patterned thin film 24 is removed to obtain a desired thin film pattern (FIG. 9(d)).

[Effects of the Invention] As described above, according to the present invention, various thin films such as metal and inorganic insulating films can be selectively grown by utilizing the difference in surface free energy of underlying materials. Furthermore, since the thickness of the thin film with low surface free energy may be just one molecular layer, it becomes possible to form ultra-fine patterns. (The method of Example 1 can form a pattern with a width of 1000 people, and the method of Example 2 can form patterns with a width of up to several 100 people.) Furthermore, it is possible to form patterns without using dry etching (
Embodiment 1.2.4.5) has the advantage that deterioration of the device due to ion bombardment during dry etching can be prevented.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of the process for explaining the present invention in detail, FIG. 2 is a diagram showing an example of a CVD apparatus used for selective growth, and FIG. 3 is a diagram showing the deposition rate of the thin film and the gas used for nucleation of the thin film. Diagrams showing flow rate dependence, FIGS. 4(a) to (c) are process sectional views showing the first embodiment of the present invention, and FIGS. 5(a) to (d)
FIG. 6(a) is a process sectional view showing the second embodiment of the present invention.
) to (e) are process sectional views showing the third embodiment of the present invention,
7(a) and (b) are process cross-sectional views showing the fourth embodiment of the present invention, and FIGS. 8(a) and (b) are cross-sectional views showing the fifth embodiment of the present invention. 9(a) to (d) are the sixth embodiment of the present invention.
It is a process sectional view showing an example. 1.5.7, 12.21.22, 23...Substrate 2.2
'...Perfluoroalkyl acrylate film 3.15.
17...Silicon oxide film 4.4'...CF3(CF,)@(CH,),,CG
COOH film 6.11... Inorganic insulating film 8... Thin film to be processed 9... Resin films 10, 13... Resin, resin film with perfluoroalkyl group 14... M film 16 ... Groove 18 ... Impurity implanted regions 19, 20 ... Electron beam 24 ... Resin or carbon film 25 ... Low surface free energy surface 26 ... Patterned thin film 27 ...・・Part where thin film is not attached 28 ・Reaction chamber 29 ・Sample 30, 31, 32 ・Flowmeter 33 ・Ring pipe patent applicant Nippon Telegraph and Telephone Corporation Representative Patent Attorney Nakamura Junnosuke 1st illustration 2nd illustration

Claims (8)

[Claims] (1) On a substrate on which a first thin film with low surface free energy has been patterned, a second thin film is selectively grown on the portions to which the first thin film is not attached using the CVD method. Characteristic thin film fine pattern formation method. (2) The first thin film is made of a first resin with low surface free energy that crosslinks or decomposes when irradiated with a photon beam or a particle beam, or a mixed resin of a photosensitive resin and the first resin, and 2. The thin film fine pattern forming method according to claim 1, wherein the patterning is carried out by developing after exposure to the photon beam or particle beam. (3) Claim 2, wherein the first resin is a resin having perfluoroalkyl in the side chain.
Thin film fine pattern formation method described in . (4) The first thin film is a film whose surface free energy is lowered by patterning a resin film or a carbon film and then fluorinating the surface with heat or plasma. The thin film fine pattern forming method according to item 1. (5) The first thin film is an organic substance having a double or triple bond that can be polymerized by a photon beam or a particle beam among chain polymers having a perfluoroalkyl group at one end and a hydrophilic group at the other end. Claim 1, characterized in that the film is a film in which a monomolecular layer or several molecular layers of is deposited on the substrate, and the patterning is performed by developing the film after exposure to the photon beam or particle beam. thin film fine pattern formation method. (6) After forming the patterned first thin film, a vapor-phase metal compound having the property of hydrolyzing and water vapor are reacted by the CVD method to selectively form the second thin film, which is an inorganic insulating film. The thin film fine pattern forming method according to claim 1, which comprises growing a thin film fine pattern. (7) Applying a second resin on the third thin film deposited on the substrate and on which a fine pattern is to be formed, and then applying the first thin film with low surface free energy on the second resin film. The first thin film is exposed and patterned using a photon beam or a particle beam, and then the second thin film is selectively applied to the portions to which the first thin film is not attached by the CVD method. A certain inorganic insulating film is deposited, the second resin film is dry-etched using the inorganic insulating film as a mask, and the third thin film is dry-etched using the dry-etched second resin film as a mask. The thin film fine pattern forming method according to claim 1, which comprises etching. (8) After forming the patterned first thin film, the metal film that is the second thin film is selectively grown by the CVD method using an organic metal gas. The thin film fine pattern forming method according to item 1.